Toxicological evaluation and bioaccumulation potential of lolitrem B, endophyte mycotoxin in Japanese black steers.

Lolitrem B, a causative toxin for ryegrass staggers, is produced by Neotyphodium lolii infecting perennial ryegrass (Lolium perenne). Japanese black cattle have been suspected to be more sensitive to lolitrem B than to other strains, and there has been a concern about the public health hazard of eating beef contaminated with lolitrem B. We carried out a feeding experiment to examine the sensitivity of Japanese black cattle to lolitrem B and the residual level of lolitrem B in several animal tissues. Japanese black steers were fed a 0, 500, 750, 1000, 1500 or 2000 µg kg(-1) diet of lolitrem B provided by endophyte-infected perennial ryegrass straw for 12 weeks. All six animals in the 2000 µg kg(-1) diet group exhibited ryegrass staggers symptoms. Furthermore, two out of three animals in the 1500 µg kg(-1) diet group, three out of six animals in the 1000 µg kg(-1) diet group and one out of three animals in the 750 µg kg(-1) diet group presented clinical signs of ryegrass staggers. These results suggest that a daily intake of 18 µg kg(-1) body weight of lolitrem B can produce ryegrass staggers in Japanese black steers. Perirenal fat tissues of the steers from those groups having one or more animals exhibiting ryegrass staggers symptoms contained approximately 150 ng g(-1) of lolitrem B, while only small amounts of lolitrem B were detected in muscle, liver and kidney. Because the residual amount of lolitrem B in tissues of Japanese black cattle is small, the exposure to lolitrem B in consumers of the beef is likely to be low.